domingo, 16 de octubre de 2011
Antarctica's Lake Vostok: A 15-million Year Old Time Capsule --Will Exploration Endanger this Living Laboratory?
"Lake Vostok is an international treasure. We have to convince not just the scientific community but the entire world that we can do this without contaminating the lake."
Karl Erb, director of the NSF Office of Polar Programs.
At the very edge of the Antarctic ice horizon — is a scattering of snow-drifted buildings and radio towers known as Vostok Station--a Russian scientific outpost on the ice above ancient Lake Vostok that researchers have manned almost continuously for 40 years.
Because of the long isolation, it's believed that Lake Vostok could contain new lifeforms, and unique geochemical processes. For five years, scientists in Russia and the United States have sought to probe the ancient lake to discover the secrets lying inside this pristine body of water. The overlying ice provides a continuous paleo-climatic record of 400,000 years, although the lake water itself may have been isolated for as long as 15 million years.
Russian researchers have thawed ice estimated to be perhaps a million years old or more from above Lake Vostok, approximately 250 km long and 50 km wide, is an ancient lake that lies hidden more than two miles beneath the frozen surface of Antarctica. Scientists are using novel genomic techniques to determine how tiny, living "time capsules" survived the ages in total darkness, in freezing cold, and without food and energy from the sun.
A major issue is the reality that it is impossible to penetrate an isolated ecosystem without contaminating it. The catch 22 inherent in Lake Vostok is that the very thing that make it potentially unique: because of its millennia of isolation from the rest of the world, it cannot be explored without introduction of microbes from the outer world.
Antarcticlakes_vostok_3 NASA has expressed interest in exploring the lake to search for microbes that might be similar to ones on other planets. How the bacteria get energy to survive is an important unanswered question. The lake could be an analog to Jupiter's moon Europa or subsurface where conditions are similar.
The ice segments were cut from an 11,866-foot ice core drilled in 1998 through a joint effort involving the United States, Russia, and France. The core was taken from approximately two miles below the surface of Antarctica and 656 feet (200 meters) above the surface of the lake, and has since been stored at -35 degrees Celsius at the National Ice Core Laboratory, Denver, Colo.
"This lake may have been isolated for that long - 15 million years," said Lanoil, the principal investigator of the research project. "After nearly a year of preparation and verifying protocols, we are now ready to process the samples, and will examine the DNA of these microorganisms to understand how they survived in such an extreme environment."
The original Russian Vostok station sits over the south end of the lake at the precise geomagnetic South Pole, surrounded by decades' worth of discarded machinery, waste and rubbish.
Over the years, the Russian scientists here have endured temperatures colder than parts of Mars, dwindling support and reflexive skepticism about the quality of their research from colleagues in Europe and the United States.
Recent financial cutbacks in the Russian Antarctic Program mean that Vostok can be resupplied just once a year. Fuel and food are hauled overland by tractors about 900 miles from the coast. Mechanical breakdowns sometimes prevent the overland tractor trains from reaching Vostok.
It was Russian scientists at Vostok Station who discovered the lake and who first realized its unique potential. Now they hope that the international effort to explore the life in the lake might benefit their own faltering research program.
In the most ambitious drilling program ever undertaken on the southernmost continent, the Russian scientists produced the world's deepest ice core, containing an irreplaceable chemical record of more than 400,000 years of Earth's changing climate and atmosphere. They did not learn of the lake's existence or appreciate its importance until the project neared completion.
But in 1998, as the drill reached within a hundred yards of the surface of the lake, they deliberately stopped. No one wanted to risk contaminating the water.
To keep the ice hole from freezing shut as they worked, however, the Russian scientists over the years pumped it full of aviation fuel and Freon. Now there is too much drilling fluid to be safely pumped out of the hole, stored aboveground, recycled or removed, Russian officials have reported.
At least 60 tons of the toxic chemicals sit in a narrow column that reaches to within a few hundred feet of the lake, like a needle poised above a bubble of expectations.
It could be years before all the difficulties have been resolved and a project can be organized to explore the lake, and a decade before its pristine waters are breached, U.S. officials said.
U.S. research communities within the Antarctic Circle are maintained by a government body--the United States Antarctic Program--that operates like a mini NASA.
In our era of rapid climate change, it's important to realize that over 6 million cubic miles, about 70% of the planet's fresh water is locked in Antarctica's ice, about 90% of which is locked up in the apparently stable East Antarctic ice sheet, set on the rocky continental surface and partly hemmed in by mountains. Scattered in pockets between miles of ice and the rock foundation , are at least 145 lakes of unknown origin, connected by streams in an entire unseen hydrologic plumbing network, a system researchers believe that may affect the stability of the ice sheets.
No other natural lake environment on Earth has this much oxygen as Lake Vostok -an oligotrophic extreme environment, one that is supersaturated with oxygen, with oxygen levels 50 times higher than those typically found in ordinary freshwater lakes. The sheer weight of the continental icecap sitting on top of Lake Vostok is believed to contribute to the high oxygen concentration. Microbial organisms in Lake Vostok must be capable of overcoming very high oxygen stress, and may have had to evolve special adaptations, such as high concentrations of protective enzymes, in order to survive.
The discovery of interconnected lakes beneath kilometers of ice in Antarctica could be one of the most important scientific finds in recent years, but proper procedures need to be established before investigation begins, says Mahlon "Chuck" Kennicutt II, professor of oceanography at Texas A&M University and a leader in the research efforts.
The National Science Foundation and 11 countries involved in the research and exploration are seeking agreement on how best to study these unique environments, which include at least 145 lakes under Antarctica's massive ice sheets.
Participants in the project known as The Russian Antarctic Expedition have announced their intentions to penetrate Lake Vostok during coming Antarctic field seasons.
"These lakes were rediscovered within the past 10 years or so, but no one yet has penetrated them and we want to make sure that the research is done properly and adheres to the highest environmental stewardship principles," says Kennicutt.
"This has the potential to be one of the most important scientific discoveries in years, since sub-ice water appears to be an important player in many different processes fundamental to Antarctica and our planet.
"We believe that these lakes are part of an interconnected system that spans the entire Antarctic continent," he adds. "These bodies of water are several miles beneath the ice sheet which took millions of years to form, meaning these lakes have been undisturbed and disconnected from our atmosphere for hundreds of thousands of years. It is highly likely that unique microbial communities that we never knew existed are lake residents."
Scientists from the countries involved, which include the U.S., France, Italy, Japan, Russia, the United Kingdom and others, have concluded that lake entry and sampling will ultimately be necessary to accomplish the ambitious research objectives.
"How to do this in the best way to preserve these environments and to be least invasive is a key question that needs further discussion," Kennicutt notes.
"The countries involved have all agreed we must do as much as possible to avoid altering the lakes or causing any environmental damage."
Research in Antarctica has always had a special set of rules among nations. It is the only continent on Earth that is managed through an international treaty signed by 45 countries representing two-thirds of the world's population. By unanimous consent of these nations, Antarctica has been viewed as a continent for science, research and peace.
Scientists believe that the lakes exert an important control over the large ice-sheet movement, and that they exist as above-ground waterways do, with streams, rivers and lakes commonplace. Believed to span underneath the entirety of the continent that is 98% ice, they represent the chance to look back several million years. With millions of years separating them from our current atmosphere, Kennicutt believes that “…It is highly likely that unique microbial communities that we never knew existed are lake residents.”
And while it is thought that it could take the US some 3-5 years to begin work itself on researching and studying the lakes, Kennicutt states that “…Once the U.S. becomes fully engaged in these research efforts, this will almost certainly be one of the dominant Antarctic research focus areas for at least the next decade, if not longer.”
The largest subglacial lake, 12,000 feet beneath the surface ice is Lake Vostok, is a body of water the size of Lake Ontario and up to 2,600 feet deep. Researchers have mapped Lake Vostok with seismic studies and ice-penetrating radar but have not seen or reached it. Its burial below the ice cap predates the rise of humans, perhaps by several million years.
No one knows if anything lives in the long-isolated lake--if not, it would be the first sterile water found on Earth. Any microbial life that does call Lake Vostok home would have to survive in a severely low-nutrient environment, without light, in near-freezing waters and at a pressure 360 times that of sea level.
Lake Vostok an excellent Earth-bound staging-experiement for Europa, a moon of Jupiter believed to have ice-crusted oceans. Scientists believe Europa's ocean, which is warmed by gravitational forces, could be one of the best places in the Solar System to look for life. A craft sent to Europa would use nuclear power to melt through the 10km of ice that cover the moon's ocean. NASA and the Jet Propulsion Laboratory have designed a "cryobot," a robot, which would generate enough heat to melt the ice around it and slowly sink into the water. Once it reaches the lake, it would release a smaller swimming "hydrobot" to collect data for future exobiological surveys.
This fall a science team led by British Antarctic Survey's (BAS) Dr Andy Smith has begun exploring ancient Lake Ellsworth hidden deep beneath Antarctica's ice sheet. As with Vostok, the lake could yield vital clues to life on Earth, climate change and future sea-level rise.
Source: The Daily Galaxy